another, especially in the case of homologous compounds, such
as occur in petroleum and coal-tar naphtha. One distillation
suffices only to produce very partial separation of the different
substances, a portion of the less volatile liquid being carried
over in the first distillate, together $iih the more volatile body,
Fi<!. 7^"» represents n seri<%s of simple and e.l'fi :iftit fnu'tinnntii)^ colunin1; or still-
heads. A is th.-it uf Vii^reux, in \vli <:h he coii-.trii'tidii1, :ir<- lonued by in-
ileiitin^ llu- tube it-.t-If; i-. is I Jnnpel's :olu nn und cmi-.i-.ts ol" a Imii.' wide tttbc
ille<i with tj;|;i-,s heads ; <•, M, and K ar<; cult nue, d.-vi-.rd by N'.MIIIV. and Tl mm-.,
1 e last brim', usci'ul wiicn lai-,j;<- ijitanii ies >f liijuid have to be di-,iillrd. con-
;ins a series ..f ^jass clisrs fused ,,n car.xl, which ran be removed IV, n the
i !>e ; D has a series of" pear-shaped I ulhs blown on the Mem, and K is; wide
i be with a series of constriciions in ea :h of \vhi<:h a small bent i',lass <lr ppin.i;
i In: is suspended in a i',an/e cup.
the temperature gradually rising tliroughont the distillation. In
only*' to effect separation of the several substances, recourse i1
had to the method of fractional distillation.
Tf|e liquid is distilled in a round flask over wire-gauze or.
better, in a fusible metal bath, a bit of ^rous pot or a coil <»i